/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)ip_output.c	8.3 (Berkeley) 1/21/94
 * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
 */

/*
 * Changes and additions relating to SLiRP are
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include "slirp/slirp.h"

u_int16_t ip_id;

/*
 * IP output.  The packet in SLIRPmbuf chain m contains a skeletal IP
 * header (with len, off, ttl, proto, tos, src, dst).
 * The SLIRPmbuf chain containing the packet will be freed.
 * The SLIRPmbuf opt, if present, will not be freed.
 */
int ip_output(so, m0) struct SLIRPsocket *so;
struct SLIRPmbuf *m0;
{
        struct ip *ip;
        struct SLIRPmbuf *m = m0;
        u_int hlen = sizeof(struct ip);
        u_int len, off;
        int error = 0;

        DEBUG_CALL("ip_output");
        DEBUG_ARG("so = %lx", (long)so);
        DEBUG_ARG("m0 = %lx", (long)m0);

        /* We do no options */
        /*	if (opt) {
         *		m = ip_insertoptions(m, opt, &len);
         *		hlen = len;
         *	}
         */
        ip = mtod(m, struct ip *);
        /*
         * Fill in IP header.
         */
        ip->ip_v = IPVERSION;
        ip->ip_off &= IP_DF;
        ip->ip_id = htons(ip_id++);
        ip->ip_hl = hlen >> 2;
        ipstat.ips_localout++;

        /*
         * Verify that we have any chance at all of being able to queue
         *      the packet or packet fragments
         */
        /* XXX Hmmm... */
        /*	if (if_queued > if_thresh && towrite <= 0) {
         *		error = ENOBUFS;
         *		goto bad;
         *	}
         */

        /*
         * If small enough for interface, can just send directly.
         */
        if ((u_int16_t)ip->ip_len <= if_mtu) {
                ip->ip_len = htons((u_int16_t)ip->ip_len);
                ip->ip_off = htons((u_int16_t)ip->ip_off);
                ip->ip_sum = 0;
                ip->ip_sum = cksum(m, hlen);

                if_output(so, m);
                goto done;
        }

        /*
         * Too large for interface; fragment if possible.
         * Must be able to put at least 8 bytes per fragment.
         */
        if (ip->ip_off & IP_DF) {
                error = -1;
                ipstat.ips_cantfrag++;
                goto bad;
        }

        len = (if_mtu - hlen) & ~7; /* ip databytes per packet */
        if (len < 8) {
                error = -1;
                goto bad;
        }

        {
                int mhlen, firstlen = len;
                struct SLIRPmbuf **mnext = &m->m_nextpkt;

                /*
                 * Loop through length of segment after first fragment,
                 * make new header and copy data of each part and link onto chain.
                 */
                m0 = m;
                mhlen = sizeof(struct ip);
                for (off = hlen + len; off < ip->ip_len; off += len) {
                        struct ip *mhip;
                        m = m_get();
                        if (m == 0) {
                                error = -1;
                                ipstat.ips_odropped++;
                                goto sendorfree;
                        }
                        m->m_data += if_maxlinkhdr;
                        mhip = mtod(m, struct ip *);
                        *mhip = *ip;

                        /* No options */
                        /*		if (hlen > sizeof (struct ip)) {
                         *			mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
                         *			mhip->ip_hl = mhlen >> 2;
                         *		}
                         */
                        m->m_len = mhlen;
                        mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
                        if (ip->ip_off & IP_MF)
                                mhip->ip_off |= IP_MF;
                        if (off + len >= (u_int16_t)ip->ip_len)
                                len = (u_int16_t)ip->ip_len - off;
                        else
                                mhip->ip_off |= IP_MF;
                        mhip->ip_len = htons((u_int16_t)(len + mhlen));

                        if (m_copy(m, m0, off, len) < 0) {
                                error = -1;
                                goto sendorfree;
                        }

                        mhip->ip_off = htons((u_int16_t)mhip->ip_off);
                        mhip->ip_sum = 0;
                        mhip->ip_sum = cksum(m, mhlen);
                        *mnext = m;
                        mnext = &m->m_nextpkt;
                        ipstat.ips_ofragments++;
                }
                /*
                 * Update first fragment by trimming what's been copied out
                 * and updating header, then send each fragment (in order).
                 */
                m = m0;
                m_adj(m, hlen + firstlen - ip->ip_len);
                ip->ip_len = htons((u_int16_t)m->m_len);
                ip->ip_off = htons((u_int16_t)(ip->ip_off | IP_MF));
                ip->ip_sum = 0;
                ip->ip_sum = cksum(m, hlen);
        sendorfree:
                for (m = m0; m; m = m0) {
                        m0 = m->m_nextpkt;
                        m->m_nextpkt = 0;
                        if (error == 0)
                                if_output(so, m);
                        else
                                m_freem(m);
                }

                if (error == 0)
                        ipstat.ips_fragmented++;
        }

done:
        return (error);

bad:
        m_freem(m0);
        goto done;
}
